Automata Inc. produces specialty vehicles by contract. The company operates several departments, each of which builds a particular vehicle, such as a limousine, a truck, a van, or an RV. Before a new vehicle is built, the department places an order with the purchasing department to request specific components. Automata’s purchasing department is interested in creating a database to keep track of orders and to accelerate the process of delivering materials. The order received by the purchasing department may contain several different items. An inventory is maintained so that the most frequently requested items are delivered almost immediately. When an order comes in, it is checked to determine whether the requested item is in inventory. If an item is not in inventory, it must be ordered from a supplier. Each item may have several suppliers. Given that functional description of the processes encountered at Automata’s purchasing department, do the following:
Automata Inc. produces specialty vehicles by contract. The company operates several departments, each of which builds a particular vehicle, such as a limousine, a truck, a van, or an RV.
Before a new vehicle is built, the department places an order with the purchasing department to request specific components. Automata’s purchasing department is interested in creating a
The order received by the purchasing department may contain several different items. An inventory is maintained so that the most frequently requested items are delivered almost immediately. When an order comes in, it is checked to determine whether the requested item is in inventory. If an item is not in inventory, it must be ordered from a supplier. Each item may have several suppliers.
Given that functional description of the processes encountered at Automata’s purchasing department, do the following:
- Define a set of business rules based on the case description. Note, you may need to make some assumptions to generate the business rules. As long as your assumptions are reasonable, you will get full points.
Example: One supplier can offer zero or many items.
2. Identify all of the main entities from the business rules. Give a list of words that represent entities.
Example: Supplier, Item
3. Identify all of the relations among entities. For each relationship, describe the involved entities, and the relationship type, e.g. 1:M, M:N or 1:1.
Example: Supplier: Item N:M
4. Draw the ERD. Please give at least three attributes for each entity.
5. Convert the ERD to relational tables and draw the tables with column names. Please also mark PK and FK (If there is one) in the table.
Example:
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ItemID (PK) |
ItemName |
ItemQuantity |
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6. Give three example queries that can be obtained from the database and design the SQL code. Example:
Query: find all items that have 0 inventory.
SQL: Select *
From Item
Where ItemQuantity=0
7. Reflection (Graduate students only): please write a short essay (about one page, double space) to discuss the following two topics:
7-a) ERD as a communication tool. Why do we need ERD? Why not creating relational models directly based on the business narrative?In practice, for the assumptions you have made in this assignment, it will be an opportunity to communicate with business users to clarify their requirements.
7-b)ERD design is an iterative process. Why can’t we design the best ERD in the first round?When you work on steps b, c, and d, did you go back and revise business rules? When you think about query examples, did you go back to ERD and change the design?
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